PTPN2 and type 1 diabetes mellitus: Notably, the variants of PTPN2 associated with autoimmunity are quite common (the minor allele frequency (MAF) of rs1893217 risk = 0.1196) and the increase in risk is modest (the odds ratios for T1D and Crohn’s are 1.3 and 1.25 respectively (27)) indicating that the risk variants contribute through modest alterations in multiple aspects of immune regulation.